A display device often includes an active matrix substrate that includes thin film transistors corresponding to a plurality of pixels, respectively. Examples of such a display device include a liquid crystal display, an organic EL display, and a microelectromechanical system (MEMS) display. The MEMS display is a display device in which mechanical shutters are used.
For example, Patent Document 1 indicated below discloses a transmission type MEMS display. In this MEMS display, on a first substrate that includes thin film transistors (also referred to as “TFTs”), a plurality of shutters of MEMS are arrayed in matrix so as to correspond to the pixels, respectively. On a light-shielding film laminated on a first-substrate-side surface of a second substrate, a plurality of openings are provided that are arrayed in matrix so as to correspond to the pixels, respectively. When the shutter portions move, the openings are opened/closed, which cause light from a backlight unit to be transmitted toward the display surface or to be blocked.
In recent years, oxide semiconductors having characteristics such as high mobility and low leakage current are used as semiconductor films for TFTs. The range of the use of the active matrix substrate that includes TFTs formed with oxide semiconductors is extending. For example, oxide semiconductors are used in liquid crystal displays that are required to be high-definition, current-driven organic EL displays in which loads on thin film transistors are large, and, MEMS displays that are required to control actions of shutters at a high speed, and the like.